During flight, an aircraft cabin is typically pressurized with air that is supplied from the engine bleed air and air conditioning systems. In the highly unlikely, yet postulated, event that airflow from these systems is lost during flight, which is generally referred to as a “loss of inflow,” fresh air ventilation still needs to be provided for the cabin occupants to ensure that carbon dioxide does not build-up to undesirable levels. Traditionally, for relatively large aircraft, this function is provided by a dedicated emergency ram air inlet valve (a ram air scoop mounted on the fuselage).
Unfortunately, dedicated emergency ram air inlet valves exhibit cost and weight penalties. As such, several attempts have been made to use existing cabin pressure control thrust recovery valves to also implement the functionality of the emergency ram air inlet valve. However, the basic shape of traditional thrust recovery valves allows some cabin air to exhaust along with the ram air inlet, which results in a lower net ingress of airflow into the aircraft cabin than desired.
Hence, there is a need for a cabin pressure control thrust recovery valve that also implements the functionality of an emergency ram air inlet valve while preventing, or at least significantly inhibiting, cabin air to exhaust along with the ram air inlet. The present invention addresses at least this need.